Paula Radcliffe and Running Efficiency

In recent weeks, I have been focusing on developing a program which will allow me to run a good marathon in 2012. Although I would not wish to rely too heavily on the training of elite athletes to guide me, I have nonetheless been quite strongly influenced by the training program that turned Paul Radcliffe from a promising junior distance runner who won the World Junior Cross Country championship in 1992 into one of the most amazing marathon runners the world has ever seen.

VO2max or efficiency?

According to Andrew Jones, the physiologist who has supervised the measurement of Paula’s aerobic capacity and running efficiency over a period of more than 15 years, the major factor in her improvement was a 15 percent increase in her running efficiency between 1991, a year before she won the World Junior Cross Country championship, and 2003 when she set a world woman’s marathon record of 2hr 15 min 25 sec in London. (International Journal of Sports Science & Coaching Vo1 • pp101-116 • 2006).

If we ignore the minor ups and downs in the measurements, her maximum aerobic capacity (VO2max ) remained approximately constant at 70 ml/min/Kg from age 17 in 1991, to age 29 in 2003. However her oxygen consumption at a pace of 16 Km/hr (6 min/mile) decreased from 205 ml/Kg/Km in 1992 to 175 ml/Kg/Km in 2003, which represents a 15% increase in efficiency (i.e. 15% reduction in the amount of oxygen consumption per Km at a standard pace).

 Andrew Jones acknowledges that he does not know which physiological variable has made the greatest contribution to this improvement in efficiency. Among the various measurements he performed were blood lactate at various paces; heart rate at various paces; vertical jump height and the sit-and-reach test of lower body flexibility. All of these measurements changed significantly over the relevant time period.

The lactate turn point

Most striking was the right shift of the turn-point in the graph of blood lactate against pace. In 1992, there was an appreciable upturn of lactate (from 1.2 to 1.45 mM/litre) between 13 and 14 Km/hour. By 2003, her blood lactate level remained almost constant in the range 1.2 – 1.4 mM/litre up to 18.5 Km/hr and then turned upwards sharply.

At first sight, this might indicate a substantial increase in ability to deliver oxygen to the tissues (perhaps via increased diameter or density of capillaries) and/ or increase in number of mitochondria in muscle fibres so that fuel is burned aerobically rather than anaerobically. However, one might expect that if such changes were generalized to all aerobic muscle fibres, these changes would also produce an increase in VO2 max. In view of the fact that VO2 max did not increase substantially, it suggests that the changes are predominantly changes in blood supply and mitochondria in slow twitch fibres.

Andrew Jones reports that during the relevant years she increased her ability to cope with a relatively large training volume, so that by 2003 she was running up to 160 miles per week. Jones reports that a large proportion of Paula’s training was steady paced running typically running at a pace of 3:30 to 3:40 min/Km. For most people, these paces would be well above the lactate turn point, though by 2003, at 3:20 min/km Paula’s blood lactate level was only about 1.4mM/litre. A large volume of training at this pace would be expected to develop the capillaries and mitochondria of slow twitch fibres. It is noteworthy that 3:20 min/Km corresponds to a marathon time of 2 hrs 20 min and thus is not far below her race pace. Thus I am inclined to speculate that it is likely that the most significant development that allowed her to run a marathon in 2:15:25 was the development of capillaries and mitochondria of slow twitch fibres.

However, it should also be noted that even at paces corresponding to VO2max, her blood lactate level was only around 5mM/litre, which is around half the expected value for a typical athlete. This suggests that she also had a highly developed capacity to metabolize lactate. This would have made her use of fuel at marathon pace more efficient.

Muscle power

In addition, other factors almost certainly contributed. As an old timer with noticeably reduced muscle power, my attention was caught by the observation that her vertical jump performance increased from 29cm in 1996 to 38cm in 2003. Perhaps the most important contribution to developing her muscle power arose from the efforts of physiotherapist Gerard Hartmann to identify the problem that had left Paula struggling in the wake of three faster runners in the final lap of the 10,000m in the Sydney Olympics in 2000.

In an article published in Running Times in 2004, athletics journalist, Frank Greally, reported an interview with Hartmann, in which Hartmann described how, after the 2000 Olympics, he had asked Paula to do 20 hops up and down from a 16 inch high box as fast as she could. Whereas Kelly Holmes had achieved 20 hops on and off the same box in 12.5 seconds, Paula took 27 seconds on her first attempt. This led Hartmann to devise a program of plyometric exercises and heavy weight sessions. In 2002, Paula won her first senior world title (long cross country in Ostend, Belgum) and also her debut marathon in London, where she achieved the second fastest time ever for woman (eight seconds slower than Catherine Ndereba’s record of 2:18:47).

Head nodding

Another problem that Hartmann had addressed following the disappointing 4th place in the 10000m in the Sydney Olympics was Paula’s characteristic head-nodding style. Hartmann demonstrated that this arose from weak neck and shoulder muscles and devised a program of strengthening exercises which has largely cured her head nodding.

Is flexibility good?

An intriguing but probably a less important factor was the deterioration in Paula’s lower body flexibility over the period from 1991 to 2003. Andrew Jones reports that in 1991, in the sit-and-reach test she reached 8cm beyond her toes in 1996, but only 4cm beyond her toes in 2003. This observation demonstrates that a high degree of flexibility is not essential for world class performance, and raises the possibility that too much flexibility might actually be associated with diminished efficiency.

Conclusion

In conclusion, the evidence suggests two major developments contributed to Paula’s increased efficiency and dramatically improved performances. The first was a strong rightward shift of the lactate turn point, possibly due largely to development of capillaries and mitochondria in slow twitch fibres and to increased ability to metabolize lactate. Secondly, a program of plyometrics and weight training led to a major increase in her leg muscle power, reflected in vertical jump capacity, and in her neck and shoulder muscles, alleviating her previous inefficient head nodding style. It is likely that the increased power of her leg muscles allowed her to spend a shorter time on stance and to lengthen her stride, in the manner described by Weyand in the study which I described in my blog post on 22nd November.

 2003 – 2012

Since 2003, Paula has continued to record great achievements in the marathon, with three victories in New York (2004, 2007 and 2008); first place in London in 2005; and a gold medal at the world championships in Helsinki in 2005. Sadly, an Olympic medal still eludes her. She now has her sights on the London Olympics 2012. By then she will be 38. I understand that Catherine Ndereba, who had preceded Paula as the woman’s marathon world record holder in 2002; won gold at the world championships in 2003 and 2007; and silver at the Olympics in Athens in 2004 and Beijing in 2008, is also planning to race in London. Catherine will be 40 in 2012. It would be wonderful if both are in great form for that race. It would be hard for anyone with a sense of sportsmanship to begrudge Paula a medal.

Whether or not Paula is able to produce medal winning form in 2012, her story illustrates that a systematic approach to training, focusing on aerobic development, leg strength and running technique has turned a promising junior into one of the most wonderful athletes ever.

Weyand v. Pose: it’s the push that counts

A few weeks ago, I presented an overview of my plan to get fit enough to run a ‘good’ marathon again in 3 years time. Each 3-4 month period will have a specific goal in addition to the continuing basic objective of improving my aerobic capacity. The specific goal for the first 4 month period is recovering some of my lost muscle strength, largely by resistance exercises and drills, together with a small amount of sprinting and uphill running.

Although I have now completed the first three weeks of the program, I have not fully settled the question of what leg strength exercises and drills are likely to be most beneficial. At present the exercises that I am doing are mainly body-weight exercises performed standing on one leg (such as one leg squats , hip swings, calf raises etc) since the major muscle actions of running are executed while standing on one leg. I am also doing a very small amount of plyometric exercise to increase my capacity to deal with eccentric contractions but in view of the risk of long term damage, I am being quite sparing with these exercises. I plan to test for gains in leg muscle strength (assessed by a hopping test, and by measuring my sprinting speed) after 6 weeks and if there has not evidence of substantial gain, I will modify the types of exercises and drills in my program.

In preparation for this, I have been once again reviewing the question of running technique in order to identify what exercises and drills are likely to be most beneficial. Two apparently coincidental happenings in the past two weeks have also served to re-focus my attention on running style.

 Gravitational torque

One has been a series of comments by Simbil on a post entitled ‘if gravitational torque is a red herring, how to do we run fast?, which I had posted in February. Simbil is a runner and thinker based in Sheffield, who contributes thought-provoking comments to the Efficient Running thread on the Fetch website. He is an advocate for Pose technique, though he is prepared to re-examine the tenets of Pose in a thoughtful manner. Gravitational torque plays a crucial role in the theory of Pose. Simbil has been challenging my assertion that the gravitational torque that generates head-forwards and downwards angular momentum in the second half of the stance phase is balanced by an oppositely directed torque acting in the first half of stance. We have been lobbing arguments back and forth for some time. We have not yet reached any definitive conclusion, though we are in agreement that the gravitational torque must be counteracted by an oppositely directed torque acting a some point in the gait cycle, and furthermore, that whatever the mechanism, the forces involved in generating gravitational torque and compensating for it are far less important that the forces required to get airborne. I will return to this issue a little later.

Pose Tech

The other coincidental happening came to my attention when I noted a little upwards blip in the number of hits on this site a little over a week ago. At present this site gets about 2000 hits per month (far below the league of the Huffington Post or Belle de Jour, or, I suspect, Younger Legs for Older Runners, but nonetheless, satisfying). Most of the hits come from Google searches seeking information about various aspects of running technique and training, though the flurry of increased activity in the few days after each posting indicates that there are also some faithful followers. It always gives me a little thrill to see these flurries of activity and I hope that those of you who read the posts find them interesting. In addition there are occasional flurries of increased activity at other times indicating that some other website has drawn attention to something on my site. One such flurry occurred last week, and inspection of the stats provided by WordPress revealed that the hits were referred from one of the forums on the Pose Tech website. Those forums are protected by password, but as runner interested in Pose, I have been registered with the site for several years. So I was tempted to have a look.

When I logged on I was intrigued to find that there was a quite active thread discussing my blog. Those of you familiar with the Pose Tech site will probably be aware that many of the people who post on the forums are strong believers in Pose. Therefore, I was more amused than surprised to see comments such as ‘burn the heretic’. However a gratifyingly number of the postings were in agreement with my views, especially my view that landing on the ball of the foot, in combination with a short time on stance places large forces on the foot, and is associated with risk of injury to metatarsals and connective tissues of the foot and ankle.

I was a little saddened by a passionate posting from Lana, the wife of Nicholas Romanov [correction: Lana is his daughter, see comments below], lamenting the fact that I and others did not give due credit to the amount of work and expertise that her husband has devoted to the Pose technique. However, while I am happy to acknowledge the work and expertise of Dr Romanov, I think there is a serious issue arising from the fact that the 2002 edition of Pose Method of Running reproduces the diagrams and photos from the first edition showing the heel held high off the ground at mid stance. In the early years, it was quite common for Pose novices to report Achilles or calf muscle problems, which I think are largely due to holding the heel off the ground. The importance of these problems was reinforced by the findings of the Capetown study (Arendse et al, Medicine & Science in Sports & Exercise: Vol 36 pp 272-277, 2004) demonstrating that Pose is associated with increased stress around the ankle, together with the reports by Ross Tucker (who assisted Dr Romanov in coaching the Pose technique in that study) that the runners in the Pose group suffered a high rate of injuries to connective tissue around the ankle (http://www.sportsscientists.com/2007/09/running-technique-part-ii-scientific.html).

When I expressed disappointment that these figures had been reproduced without anything in either text or illustrations (as far as I have been able to ascertain) describing how the risk of these injuries might be minimized by relaxing the ankle to allow the heel to touch the ground, Lana suggested that ‘you need to “zoom out” a bit – because you are not doing yourself any favours by using a magnifying glass all the time’. In an email, a good friend has suggested that it is unlikely that I will be on Lana’s Christmas card list this year.

Despite this little storm in a tea-cup on Pose Tech, I have a fairly positive view of how Pose works in practice, based not only on looking at the evidence through a magnifying glass; but also by talking to runners who have applied it; and by experimenting with it myself. I am less impressed with the theory underlying Pose, but the evidence that the technique can be beneficial makes me want to understand more clearly why it works

A subjective overview of Pose

Many of the principles of Pose such as high cadence, short time of stance; avoiding reaching out with the leading foot, and keeping the pelvis forward, make mechanical sense. I discuss these features in my own account of technique (‘Running: a dance with the devil’ – listed on the side panel). Many elite athletes exhibit these features despite never having been trained in Pose, though I think Nicholas Romanov deserves credit for publicizing these principles among amateur runners.

Other features such as landing on the ball of the foot (BOF) also make sense, but are attended by risk. As I had mentioned in my comments on Pose Tech that provoked the anguished response from Lana, BOF landing places substantial stress on the bones and connective tissue of the foot and lower leg, and creates a risk of repetitive strain injury to metatarsal, planate fascia, Achilles tendon and peroneal tendons. At least when running long distances, I consider it is best to relax the ankle so that the heel brushes the ground in mid-stance

I also consider that Dr Romanov’s claim that gravitational torque provides the motive force for running is misleading. According to the law of conservation of energy, it is impossible for gravity to provide net energy when running on a level surface. I accept that the unbalancing due to gravitational torque during the second half of stance does help promote the muscular actions necessary to swing the leg forwards in time to support the body at subsequent footfall. However I am not convinced that this is plays a major role, and I therefore consider that gravitational torque is probably a red herring. Nonetheless, I am quite happy to continue debating this issue with Simbil.

However in my opinion the most interesting issue for debate is the concept of pulling from stance rather than pushing. The Pose mantra is ‘Pose, Fall, Pull’ implying that the crucial actions are:

1) adopting the classic pose with the point of support (BOF), hips, and shoulders aligned, in mid-stance;

2) falling under the influence of gravitational torque as the centre of mass moves in front of the point of support;

3) pulling the leg from stance by means of a contraction of the hamstrings.

In practice, I think that getting airborne is impossible without a push. Pulling from stance would amount to lifting oneself by one’s own boot straps. Of course pulling the leg forwards by hip flexor contraction once airborne is essential, but is largely automatic. While I think that pulling from stance is largely an illusion, I think it might be a useful illusion to cultivate because it encourages a short time of stance, high cadence and relatively short strides – possibly not the best style for record breaking performances, but nonetheless fairly safe. For most of us, avoiding injury is more important than maximizing mechanical efficiency.

So, while I think that the Pose concept of pull is not mechanically correct, I think that it is a useful mental image to cultivate, in the same way that some of the principles of Alexander technique are based on creating helpful illusions. Therefore, Pose drills such as Change of Stance that encourage the illusion of pulling are probably useful. But if one want to increase one’s speed of running, are Pose drills more important that developing the muscles responsible for the push?

Weyand: it’s the push that counts

Perhaps the most important evidence about the muscular action required for running fast comes from a study by Peter Weyand and colleagues from Harvard (J Appl Physiol Vol 89: pp 1991–1999, 2000). In a study of runners with various different maximum running speeds, using a force plate to assess ground reaction forces during treadmill running, they demonstrated that ‘human runners reach faster top speeds not by repositioning their limbs more rapidly in the air, but by applying greater support forces to the ground.’ The force plate data showed clearly that a larger vertical ground reaction force achieved by the foot pushing against the ground was the main factor distinguishing fast runners from slower runners.

The extensor paradox

However, Weyand’s findings present a problem: the extensor paradox. Studies employing electromyography to measure the electrical activity in muscles demonstrate the major muscle groups that would be expected to execute a push off the ground, especially the quadriceps which are responsible for knee extension, are almost silent in late stance (Elliot et al. Medicine & Science in Sports vol 11, pp 322-327, 1979). So where does the push come from? Much of it almost certainly comes from elastic recoil of quadriceps, acting in conjunction with the hamstrings, and soleus, all of which have been stretched on impact at foot fall. Thus the crucial strength that is required for running fast is the ability to sustain a strong eccentric contraction of the quads, hams and calf muscles.

Conclusions

In a program to rebuild the strength necessary to run fast, it is crucial to recover the capacity for strong eccentric contraction of quads, hams and calf muscles. Of course other muscles also play a role – especially the gluteals which help hold the pelvis in a horizontal position during swing, and the hip flexors, which drive the swinging leg forwards – but Weyand’s study indicates that it is the ability to push strongly that distinguishes fast runners from slow runners. Clearly any strengthening program should involve a reasonable balance between all relevant muscle groups as muscles do not work in isolation, but nonetheless, much of the focus should be on eccentric strengthening of quads, hams and calf muscles.

However there is a problem: as I have discussed several times previously on this blog, eccentric contraction damages muscle, possibly permanently, especially in older runners. So a program of plyometrics designed to increase the ability to withstand eccentric contraction must be undertaken cautiously. I am inclined to think that the first priority is to recover strength of the major muscle groups, especially quads and hams with a program of resistance training with free weights, including a gradual build up of eccentric loading, before moving on to a modest amount of plyometrics. Meanwhile, I will also continue with regular uphill running, as this invokes the required muscular actions in a way that is ‘natural’ for a runner.

As for drills, any drill that promotes a short time on stance is likely to be beneficial. I am still exploring the options, but despite my opinion that the pull is less important than the push in getting airborne, I think that the Pose ‘Change of Stance’ drill is beneficial, even if it is largely cultivating a beneficial illusion of pulling from stance.

Train a lot but train smart

In proposing the toast at a dinner celebrating Espen Tǿnnessen’s successful defence of his PhD thesis, in Oslo in June 2009, Dag Kaas, coach of world champion cross-country skiers and orienteers remarked, ”My experience as a coach tells me that to become world champion in endurance disciplines, you have to train SMART, AND you have to train a LOT. One without the other is insufficient.”

This anecdote is recounted in an excellent review by Stephen Seiler and Espen Tǿnnessen entitled ‘ Intervals, Thresholds, and Long Slow Distance: the Role of Intensity and Duration in Endurance Training’ published this month in Sportscience (Vol 13, 32-53, 2009). Simon Wegeriff had provided a link to this in his comment on my post on 8th November describing the study by Esteve-Lanao. Esteve-Lanoa and colleagues provided a fairly convincing demonstration that a polarized training program in which about 80% of the work is done at low intensity, is more effective that a program including a higher proportion of work in the mid-zone, near to lactate threshold.

In their review, Seiler and Tǿnnessen present a contrast between the mixed bag of evidence from scientific studies of benefits of high intensity v low intensity training, with the observations from the training of selected elite endurance athletes. To obtain a full appreciation of the evidence it is best to read the full review. Here I will focus on a few issues that caught my attention.

Who are the authors?

Perhaps the first issue when reading a selective review article is appreciating the background of the authors. There is no reason to doubt that Seiler and Tǿnnessen are rigorous scientists with a commitment to establishing the truth. However, a scientist’s background inevitably influences the way in which evidence is selected and evaluated. The senior author, Stephen Seiler, is a strong advocate for polarized training: a large amount of low intensity training, together with a small amount of high intensity training, and a minimal amount on the intervening grey zone. He was one of the co-authors of the report on the Esteve-Lanao study, and had also previously led a study of autonomic recovery following low, medium and high intensity sessions, in which the low intensity sessions were associated with the most rapid recovery. Espen Tǿnnessen’s doctoral dissertation included detailed analyses of the training of selected world champion female endurance athletes. He examined training diary logs of over 15,000 training sessions from three World and/or Olympic champions: Bente Skari (cross-country skier), Hanne Staff (orienteer) and Ingrid Kristiansen (marathon runner). The feature common to the selected champions from the three disciplines was that about 85 % of their training sessions were performed as continuous efforts at low to moderate intensity (with blood lactate less than 2 mM).

Thus, Seiler and Tǿnnessen had good reason to approach this review with a bias towards polarized training. The bias shows through in the use of phrases such as ‘In view of the recent hype and the explosion in the number of studies investigating interval training…’ While their selection of data includes studies favoring high intensity training in addition to studies favoring low intensity training, to my eye, there is a degree of bias in the selection.

Evidence regarding African training

For example, in discussing the training programs of Africans they start with the challenging statement: ‘Kenyan runners are often mythologized for the high intensity of their training’ and go on to refer to their own re-analysis of the data collected by Veronque Billat which led them to conclude that elite Kenyan 5- and 10-km runners ran ~85 % of their weekly training kilometers below lactate-threshold speed. However, they make no mention of the study in which Tim Noakes and colleagues compared elite black African runners with elite white Africans and found that the black runners did 36% of their running at above 80% of VO2max, while the white runners did only 14% of their running above this level (Journal of Applied Physiology, vol. 75, pp.1822-1827, 1993).

Training logs of elite athletes

Seiler and Tǿnnessen present compelling evidence for major improvements in both performance and in physiological variables such as VO2max, after a change to a training program with a higher proportion of low intensity training, in the case of two Norwegian athletes: Øystein Sylta, and Knut Anders Fostervold. Sylta was a military pentathlete, who was European champion in 2003, and subsequently became an elite distance runner. Fostervold was a professional soccer player who switched to cycling after a knee injury ended his football career at age 30. He subsequently represented Norway in the world championship time trials in 2006 and 2007.

However, they make no mention of Norway’s greatest female marathon runner, Grete Waitz , who won the New York marathon 9 times, a silver medal in the 1984 Olympics in LosAngeles, and gold at the 1983 World Championships. As far as I have been able to determine, Waitz did a lot of training at mid and high intensity. For example, in an article by elite Norwegian distance runner Marius Bakken, based on Waitz’ training diary; and on talks between magazine writer, Lief Tjelta and Waitz herself; and also on talks between Bakken and one of Waitz’ mentors, Johan Kagestad, Bakken claims: ‘The most mileage for one week came in 1976 with 180 km/week. Her mileage at this time was never long and slow. She often ran it with the boys at a steady 3.30-3.45/km pace, which is quick for a female athlete (according to Kagestad). This indicates a sub AT type training to build endurance.’ http://www.mariusbakken.com/index.php?parent=11&groupid=22   Marius Bakken has a reputation for racing with tiger-like ferocity and tends to advocate a substantial amount of moderate and high intensity training. It might be possible to offer alternative interpretations of Grete Waitz’ training diary. The point I wish to make is that in the much debated question of the merits of high intensity v low intensity (high volume) training, one needs to take account of possible biases in the way in which the data is selected and presented. Notwithstanding this important caveat, I think Seiler and Tǿnnessen present a large amount of very valuable information in their review.

Differing physiological benefits at different intensities

Among the things that struck me was their discussion of the possible differences in the physiological benefits of high intensity and of low intensity, high volume training. They conclude that both forms of training are likely to lead to increased activation of fast twitch muscle fibres producing a beneficial increase in metabolic activity in these fast fibres. High intensity training will recruit these fibres early. In the case of low intensity, high volume training they propose that the fast fibres will be recruited after exhaustion of slow fibres. It might be expected that this benefit would greatest after long runs –suggesting that one long run might be better for this purpose than two shorter runs. They also indicate that high intensity training will produce increased filling of the heart and increased end-diastolic volume, thereby producing a beneficial increase in maximum stroke volume and maximum cardiac output. In addition they propose that high intensity training might lead to increased vascular supply to muscle fibres as a result of local mechanical and metabolic signals. In addtion, they  list several other possible physiological benefits of each type of training. The overall conclusion appears to be that high intensity training is likely to be more efficient for certain types of beneficial physiological development, especially in the cardiovascular system, but low intensity training also has its advantages. Thus, ‘smart’ training should include an appropriate proportion of high intensity training in addition to low intensity training. It is crucial to note that Seiler and Tǿnnessen do not argue against the inclusion of high intensity training; they are mainly arguing for polarized training with a relatively small proportion of high intensity training and avoidance of the ‘grey’ mid-zone. They argue that tiredness from mid-zone training impedes the ability to perform the high intensity sessions well.

Differences between individuals

Another important point raised by Seiler and Tǿnnessen is that individuals differ. They describe a 2 year study of cross-country skiers by Gaskill and colleagues, in which all the athletes trained similarly with about 16% of training at lactate threshold or higher, in the first year. By the end of the first year, half of the athletes had shown substantial improvement in race performance and in physiological measurements. In the second year, those who had shown improvement continued on their established training program, while those who had not improved in the first year, undertook a program with more high intensity training. In the second year, the previously poor responders improved significantly on the higher intensity program, while the previously good responders continued to improve on the established program with only 16% at or above lactate threshold. I think the lesson is that whatever program one adopts, one must monitor progress and change if the expected improvement is not occurring.

Training smart

Overall, I consider that Seiler and Tǿnnessen present a strong case for polarized training with a high proportion of low intensity sessions. However, I also think that Dag Kaas is right: it is necessary to be smart in addition to training a lot. Each individual needs to work out a program that addresses his or her specific needs; invest faith in that program for an adequate length of time while monitoring progress, and if progress is not occurring, make appropriate adjustment. In my next two posts I intend to deal with what adjustments in a training program are required to deal with some of the limitations of the older runner, and I will also describe the testing procedures that I am incorporating in my own program.

The grey zone

In recent posts I have discussed the evidence regarding the relative merits of high intensity training and high volume training.  The evidence demonstrates that both approaches are effective for increasing aerobic capacity.  Both will develop capillaries and mitochondria in heart and skeletal muscles.  High intensity training allows a more efficient use of time, which might be the decisive feature for an amateur athlete with family and work commitments, though in general, high intensity work-outs are tougher and require greater determination. 

Potential benefits of mixing high and low intensity

Furthermore the two approaches are each attended by risk of injury or over-training.  However it is probable that the risk of injury and over-training associated with the two intensities of training arise from somewhat different stresses on the body.  High intensity training produces greater forces on the musculo-skeletal system, but also produces greater increases in anabolic hormones, whereas high volume training produces greater increases in catabolic steroids such as cortisol, which can promote destruction of muscle if excessive.  On the other hand, there is relatively little evidence suggesting that a high intensity session undoes the benefits of a preceding low intensity session or vice versa.  Therefore, my provisional conclusion is that the best approach is a program that includes a mixture of high intensity and low intensity (high volume) sessions, on the grounds that such an approach is likely to achieve a good balance between stimulation of catabolic and anabolic hormones. This remains unproven but is at least plausible.

What about the mid-zone?

However, this leaves unanswered the question of whether or not training sessions that fall in the mid-zone between high intensity and low intensity (but high volume) are of much value.  Surveys have shown that elite athletes tend to avoid the ‘grey’ zone between high intensity and low intensity,  For example, the study by Seiler and Kieland found that elite skiers do about 75% of their training at low intensity and 15-20% at high intensity with only around 5-10% in the mid intensity range  (Scand J Med Sci Sports. 16(1):49-56, 2006).  Previously the French exercise physiologist, Veronique Billat, had reported similar proportions of time in the different training zones in marathon runners (Med. Sci. Sports Exerc. 33:2089–2097. 2001)

The Esteve-Lanao study

It was therefore with great interest that I read a report on a study by Jonathan Esteve-Lanao and colleagues (Journal of Strength and Conditioning Research, 21(3), 943–949, 2007), which had been pointed out to me by Simon in a comment on my post comparing high and low intensity training on October 25^th.   Esteve-Lanoa is a coach in Madrid who had previously published findings demonstrating that the proportion of training time spent in the low intensity zone was a strong predictor of race performance (Med Sci Sports Exerc. 37(3):496-504, 2005.) 

In the more recent study published in 2007, he allocated a group of well-trained sub-elite athletes to one of two programs for a period of 5 months: one program included more low intensity training than usual for this group of athletes; the other involved less low intensity training and more mid-intensity training.  Both groups performed the same amount of high intensity training.  Intensity was assessed according to proportion of training time with heart rate within low, mid and high intensity zones defined relative to the ventilatory threshold (VT) and respiratory compensation threshold (RCT). 

Defining the zones:  VT is the first appreciable step in respiratory effort as work load increases, and corresponds to the threshold described as VT1 by some authors (eg Dekerle and colleagues) or aerobic threshold by others.  It is the highest work rate that can be fueled virtually entirely via aerobic metabolism. At higher work rates, appreciable anaerobic metabolism occurs, and lactate level rise appreciably above resting values.  The increased acidity in the blood causes the noticeable rise in respiratory effort necessary to remove more carbon dioxide, thereby compensating for the lactic acid by reducing the acidity due to dissolved carbon dioxide.   Lactate is removed by organs such as liver and heart which can use lactate to generate energy.   As work rate rises further, a stage is reached beyond which the body cannot remove the lactate as fast as it is produced.  At this stage lactate level and acidity rises rapidly.  There is a major drive to increase respiratory effort in an attempt to compensate for the acidity.  This is the respiratory compensation threshold (RCT), which is also known as VT2 or anaerobic threshold.   Thus, in the study by Esteve-Lanao, low intensity training at a heart rate below that corresponding to VT is virtually entirely aerobic.  In the mid-intensity zone between VT and RCT, training involves some anaerobic metabolism but the body can cope with the rate of lactate production and lactate level remains only a little above resting value.  In the high intensity zone above RCT, a large proportion of the energy is generated by anaerobic metabolism and the level of lactate rises to high levels, compelling the athlete to make a very strong respiratory effort in an attempt to deal with the rising acidity. 

The results:  In the group assigned to an increased amount of low intensity training, the amounts of times in heart rate zones corresponding to low, mid and high intensity training were in the ratio 80:12:8 (i.e. 80% low intensity).  For the group assigned to decreased low zone training, the ratio was 67:25:8  (i.e. 13% less in the low zone, replaced by 13% more in the mid-zone).  In both groups VT occurred at approximately 67-68% of VO2max, while RCT occurred at approximately 87-88% of VO2max.  The outcome of training was assessed by comparing time recorded in a 10.4Km cross country race before and after the 5 month period of training.  The group who had HR in the low zone for 80% of the time improved by 7.5% while the group who had HR in the low zone for only 67% of training time, improved by 5%.  The difference between groups in amount of improvement was statistically significant.  It should be noted that the individuals with HR in the low zone for 80% of the time spent more hours training (average 100 hours over 18 weeks compared with average 75 hours in the group with HR in the low zone for 67% of the time), but the total load (volume x intensity) was similar in the two groups. The authors conclude: ‘These results provide experimental evidence supporting the value of a relatively large percentage of low-intensity training over a long period, provided that the contribution of high-intensity training remains sufficient.’

It is crucial to note that even the group with 80% low intensity training performed a substantial amount of demanding work. They did 2 intense sessions per week in many of the weeks, in addition to regular weight training, and also running 5 cross country races (2 x 5Km and 3 x 10Km) not including the final assessment. Nonetheless, I think the practical conclusion is that training in the mid-zone produces less benefit that a similar work load (volume x intensity) in the low zone provided the program includes sufficient high intensity work.

It should also be noted that the amount of time spent with heart rate corresponding to the mid-zone intensity does not correspond exactly to the amount of time spent working in this zone.  Typically in an interval session, it takes from 1 to 2 minutes for HR to reach the high intensity zone (due to buffering by myoglobin) during high intensity epochs, and it takes 1 to 2 minutes before HR falls back to low zone level during the recovery.  When I do 1 Km intervals, my heart rate is in the mid-zone for more than half of the session despite the fact that I do not spend any time running at a mid-zone pace.   To achieve 8% of training time in the high intensity zone typically would require about 15% of sessions to be high intensity sessions.   

On the whole this appears to be a sensibly designed and well executed study.  The main concern I would raise is the fact that Esteve-Lanao’s previous study published in 2005, in which he found that the amount of low intensity training predicted race performance, might have inclined him to have greater faith in low intensity training.  He coached all the athletes in the study reported in 2007.  There is evidence that having faith in a particular training program influences the physiological benefits from that program.  It is therefore possible that coach’s confidence in the low intensity program influenced the outcome.   It is because of unconscious influences of this sort that double-blindness is regarded as so important in trials of medical treatments.  Nonetheless, despite this potential short-coming, I consider that this study provides moderately strong support for the proposal that mid-aerobic ‘grey zone training’ is a limited value.

The beginning of a 3 year program

As described in my post on 25^th October, the events of the past summer indicate that I need to plan a long term campaign if I am ever to recover a level of fitness equivalent to that of my younger days, after allowing for the anticipated rate of decline with age illustrated by the WAVA charts.   My goal is to run a ‘good’ marathon in 2012, perhaps aiming for a target time in the range 3:15 to 3:30, and to continue to enjoy running for many years after.

What needs to be developed, and how can the required development be achieved? 

1)    Aerobic capacity of leg muscles: the ability to generate energy for muscle contraction by aerobic metabolism is crucial. The aspects of aerobic metabolism that can be improved by training are:

a.  Delivery of oxygen to the muscles – the number and size of capillaries increases when there is demand for increased delivery of oxygen to muscles;  development is likely to continue over many years provided the there is continuing demand for increased oxygen delivery.   Both low intensity and high intensity training are effective.  The study by Ingjer (J. Physiol. Vol  294, pp. 419-432, 1979) reported an increase of 28.8% in the number of capillaries per muscle fibre after 24 weeks of a high intensity program that included two interval sessions per week in addition to 3 sessions of continuous running for 45 minutes at a work rate ranging from 50 to 90% of VO2max.

 b. The number of mitochondria in type 1 (slow twitch) and type 2A (aerobic fast twitch) fibres. The mitochondria are the sub-cellular organelles containing cytochrome oxidase, the key enzyme in aerobic metabolism.  Dudley’s studies of rats (J Appl. Physiology, vol. 53, pp. 844-850, 1982), discussed in my post on 25^th October, demonstrate that increase in cytochrome C is achieved most efficiently for both type 1 and type 2A fibres at high intensity running at above lactate threshold.  Similarly, in the case of humans, the study by Gibala and colleagues (J Physiol Vol 575, pp 901-911, 2006) suggests that high intensity training is the most efficient for producing increases in muscle oxidative capacity.

Although the evidence suggests that the most efficient way to increase capillary density and number of mitochondria in skeletal muscle in the short term is via fairly high intensity running (above lactate threshold) there is no clear evidence that the benefit of such high intensity training continue to accumulate over a period of several years.  I am not aware of any systematic scientific studies that have compared groups of athletes undergoing different training regimes extending over several years. 

There are very few elite athletes who are reported to have shown continuous improvement over many years of predominantly high intensity training.  Individuals such as Gordon Pirie, who did a large number of high intensity interval sessions, had a relatively brief period at the top.  In 1956 he broke the world 3000m record twice, and won a silver medal in the 5000m at the Melbourne Olympics, but he never reached such heights again.  Emil Zatopek was a dominant force for somewhat longer winning a gold medal in the 10,000m London in 1948 and three gold medals in Helsinki in 1952, but it is probable that his famous high intensity sessions (e.g. 50×400m) were run at a relatively modest pace – perhaps around 10K pace – as reported in a comment on my blog by Ewen on 31^st March 2009 . 

In the absence of observational evidence, it is necessary to rely on our understanding of physiological mechanisms.  Potentially the most important issue is oxidative damage due to free radical production.  Both aerobic and anaerobic exercise result in the production of free radicals that have the potential to damage tissue, but provided the amount of exercise is not excessive, the body’s natural defenses can cope.  However both excessive intensity and excessive volume can result in the natural defenses being overwhelmed (Fisher-Wellman and Bloomer, Dynamic Medicine, vol 8, 2009, doi:10.1186/1476-5918-8-1)  In light of this evidence I think that the best strategy to produce continued improvement in aerobic capacity over a period of several years, is likely to be a compromise.  I plan to do an a moderate amount of interval training near to lactate threshold or a little above, but will balance this with an approximately equal amount of low to mid –aerobic running; and some non-demanding exercise focused on improving flexibility and proprioception.  

2) Increased capacity of the heart to pump blood.  Cardiac output is the product of stroke volume and heart rate. Unfortunately the decrease in maximum heart rate with age is one of the major contributors to deterioration in maximum rate of oxygen utilization with age, and there appears to be little that can be done to prevent this.  Stroke volume is determined by the difference between the volume of the left ventricle at the beginning and end of ventricular contraction (systole).  Similarly to the situation with training to increase aerobic capacity of muscles, the evidence indicates that high intensity interval training is the most efficient way to increase stroke volume.   The study by Helgerud and colleagues from Trondheim in Norway (Med Sci Sports Exerc. 39(4):665-71; 2007), which I described in some detail in my post of 23^rd June 2009 demonstrated that 4x 4 min of running at 90-95% HRmax followed by 3 min of active resting at 70%HRmax, 3 times per week for 8 weeks produces a greater increase stroke volume and also increase in VO2 max than the same number of sessions of either long slow distance running at 70%of maximum heart rate, or tempo running at around lactate threshold. 

However, as in the case of aerobic development of skeletal muscle, the goal of producing continuous development over a period of years must take account of the risk of free radical damage, and I think the same compromise program that balances intensity and volume, non-demanding exercise, and rest is likely to be optimal. 

3) Leg muscle strength and power:  Although I have never formally tested my leg muscle strength, I know from my reduced ability to step upwards onto a chair while carrying a heavy object  that my muscle strength has decreased with age.  My reduced stride length when sprinting confirms this loss of strength and power.  My current time for 100m is 18 sec. I never recorded a 100m time as a youngster, but could certainly run a 400m in much less than 60 sec, so I have clearly slowed down when sprinting and this is almost certainly due to loss of muscle power.  Running entails eccentric contraction of quads, hams and calf muscles.  However, developing eccentric muscle strength presents problems, because eccentric forces tear muscle fibres.  The most efficient way to increase strength of eccentric contraction is plyometric exercise, but the sharply applied stretching of muscles during plyometrics causes extensive damage, which is also likely to produce production of free radicals and a risk of long-term damage (Bloomer RJ & Goldfarb AH. Canadian Journal of Applied Physiology, 29(3): 245–263, 2004.)   Therefore, I will engage in weekly strength training, employing exercises that entail moderate eccentric stress, and very sparing amounts of plyometric exercise.

4) Neuromuscular coordination:  In recent years I have worked on developing a style of running that I believe is efficient and fairly safe – described in the pages ‘Running – a dance with the devil’ in the side bar of my blog.  This style is closely related to Pose, but I have tried to avoid what I perceive as the problems with Pose.  I have not yet focussed on applying this style to faster running.  In the near future, I will spend a session per week practicing this style of running at ‘near sprinting’ pace, but over short distances and with adequate recovery to minimize exhaustion. 

 

Other metabolic and musculo-skeletal developments

There are many other metabolic developments, such as increased ability to store glucose; to burn fats; to metabolize lactate, and musculo-skeletal developments such as resilience of connective tissues that I anticipate are best developed within the context of a comprehensive program focusing on the four key elements described above   

 

The program

I plan a periodized program comprising periods of several months duration within which I will spend several sessions a week focusing on the development of specific aspect of fitness, while maintaining a continuous background of aerobic development.  In addition I will spend one or two sessions per week on core strength, balance and proprioception.

Taking account the above considerations, here is my proposed program for the next 4 months:

 

Specific goal: increasing leg muscle strength and neuromuscular coordination.  The program will include the following sessions:

1) body-weight exercises that entail moderate eccentric load on the major leg muscles: hams, quads, gastrocnemius, soleus, peroneals, gluteals and tensor fascia lata (1/2 hour per week);

2) short hills (approx 90 seconds, 4-8 reps at  ¾ pace effort) on alternate weeks.

3) running style sessions:  mainly drills and short stride-outs focusing on a relaxed style.

 

Aerobic and cardiac development:

1)      Two interval sessions per week on the elliptical cross trainer.

2)      One long(ish) run: approximately 15Km at whatever pace appeals to me on the day.  I anticipate that these runs will mainly be progressive runs starting in the low aerobic zone and increasing to mid aerobic or upper aerobic zone for the final few Km, though on some occasions I will include 5-10 Km of fartlek within the 15 Km run.

 

Core strength, balance and proprioception

1)      body-weight exercises designed to improve core strength (1/2 hr per week)

2)      exploration of Yoga postures suitable for development of balance, flexibility and mental focus (1/2 hour per week)

This program entails 7 or 8 sessions of quite diverse content, per week, requiring a total duration of 4 ½ to 5 hours.  The amount of running in this 4 month period is intended to be modest, including one weekly 15Km run; a weekly running style session; and a short hill session on alternate weeks, while I focus on leg strength and neuromuscular coordination.  I anticipate that the most demanding sessions will be the elliptical interval sessions.   These will provide a substantial work-out for the cardiovascular system but due to the fact that the elliptical action involves no impact and relatively little eccentric contraction of leg muscles, the stress on the legs is relatively mild.

I will aim to do at least 80% of the scheduled sessions, but will occasionally substitute other activities such as hill walking, swimming, cycling or kayaking, as the opportunities present themselves

My provisional plan beyond this 4 month period is to devote 2 months to specific preparation for a 10K race in spring.  The major change will be the replacement of some of the elliptical sessions and strength sessions by interval and tempo running sessions.  Then during the summer of 2010, I will prepare for a half marathon in autumn.